In April 2009 a human outbreak of swine flu was confirmed in many countries including Mexico and USA, and then spread rapidly across the globe. A pandemic was declared by the WHO in June 2009. The disease was caused by a newly identified swine influenza virus A/California/04/2009 A(H1N1). This swine flu strain seems to have no immunological cross-reactivity with current human influenza vaccines strains, including the A(H1N1) antigens in current human seasonal vaccines. The virus has been referred to variously as ‘swine influenza’, ‘novel swine-origin H1N1 influenza’, ‘human-swine influenza’, ‘novel influenza A(H1N1)’ and ‘influenza A(H1N1)v’.
There is a need for a vaccine to prevent further human-to-human transmission of this swine flu and variants of it.